For the packaging of packs of several beverage containers and/or bottles, the beverage containers and/or bottles are grouped on horizontal conveying means and arranged in groups having a defined number of containers. This defined number of grouped containers is usually provided with a film wrapping for more convenient handling so that the packs may be easily transported, stacked and, if necessary, also presented in a sales room in this pack form.
The film wrapping is wrapped around the pack with the help of suitable means and subsequently shrunk by way of heating such that the pack is tightly enclosed by the taut film so that it may be easily transported and handled. In order to heat the film, the packs are usually introduced in a heating chamber, a so-called shrink tunnel, where the temperature is sufficiently high to shrink the film to a desired extent. The high temperatures are usually generated by fan heaters. When passing through the shrink tunnel, the packs are normally positioned on a horizontal conveying means, usually a metal conveyor chain.
When passing through the heating zone, the conveyor belt, e.g. a conveyor chain, absorbs thermal energy, which is at least partially released downstream of the heating zone in order to cool the packs. This results in a quite significant loss of energy from the heated zone, which must be compensated by increased heat supply in the shrink tunnel. On the other hand, the cyclic heating and cooling of the conveyor belt or chain involves the risk that heat stored and not completely released will result in an elevated temperature of the conveyor belt, which might exceed the allowable contact temperature for the film packaging, because the melting temperature thereof may be reached. If, however, the film is softened and/or melted in places, this may result in damage thereto and/or in pieces of film adhering to the conveyor belt.
Applying a suitable coating or wrapping or sheathing to the conveyor belt may reduce the effect of adhering pieces and rests of film. Such a coating and/or wrapping and/or sheathing may, for example, be made of PTFE plastic, as already known from the food industry.
For example, U.S. Pat. No. 3,646,880 shows a cooking means, a so-called cooking grill, comprising a PTFE-coated conveyor belt for positioning food to be cooked thereon. The coating is provided to prevent food to be cooked from adhering to the conveyor belt.
Also, EP 0 655 215 A1 discloses a cooking means having an endless conveyor belt for cooking food thereon. The conveyor belt is used for transporting and simultaneously cooking the food. The conveyor belt consists of a PTFE-coated plastic belt. Again, the coating serves for preventing the food to be cooked from adhering to the conveyor belt.